Tape reel, recording tape cartridge, take-up reel, pullout member, and drive device

ABSTRACT

In a tape reel that includes a hub around which recording tape is wound and flanges disposed on both end portions of the hub, the elastic modulus in a radial direction of the hub is equal to or greater than 16.0 GPa, and the hub includes different radii on one end side thereof and another end side thereof. The recording tape is wound around the hub such that the side where the radius of curvature of the curvature of a tape edge of the recording tape is small corresponds to the small radius side of the hub. When the recording tape is wound around the hub, fluctuation of the recording tape in an axial direction of the hub is controlled, and one-layer protrusion and disorderly winding of the recording tape that has been wound around the hub are controlled.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2007-119574, the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tape reel and a take-up reel around which is wound recording tape such as magnetic tape used as a recording and playback medium mainly for computers and the like, a recording tape cartridge where the tape reel is housed inside a case, a pullout member that pulls out the recording tape from the tape reel inside the case, and a drive device into which the recording tape cartridge is loaded.

2. Description of the Related Art

Conventionally, a recording tape cartridge has been known where recording tape such as magnetic tape used as a data recording and playback medium for computers and the like is wound around a reel and the reel is singly housed inside a case. When the recording tape cartridge is loaded into a drive device, the recording tape is pulled out via a leader member from an opening disposed in the recording tape cartridge. Then, the recording tape that has been pulled out is taken up onto a take-up reel that is disposed on the opposite side or the like of the recording tape cartridge, with tape guides and a recording and playback head being interposed between the take-up reel and the recording tape cartridge.

Particularly in recording and playback systems (drive devices) that use recent recording tape cartridges whose recording density has been improved, a format where the recording and playback head is moved in a vertical direction by an actuator on the basis of servo signals that have been prerecorded on the recording tape and where the recording and playback head is caused to follow the servo signals and record and play back data signals is becoming mainstream. Consequently, it is desirable for the recording tape that has been pulled out from the recording tape cartridge to be supported by plural tape guides inside the drive device and to be controlled such that the recording tape always travels along a predetermined position of the recording and playback head.

However, in actuality, phenomena such as so-called “one-layer protrusion” occur where, even though the recording tape is supported by tape guides, the recording tape fluctuates in an axial direction (vertical direction) of a hub (winding core portion) during travel, the recording tape that has been wound around the hub becomes disorderly wound, and a portion of the recording tape equal to one circling of the hub protrudes from a winding surface of the recording tape. In FIG. 24, there is shown a state of disorderly winding such as a step or one-layer protrusion from the winding surface of the recording tape (it will be noted that, in FIG. 24, the winding surface of an upper tape edge of the recording tape is shown, so one-layer protrusion and the like from the winding surface of the recording tape is observed on a lower tape edge side of the recording tape).

When such disorderly winding fluctuates particularly in a short amount of time (when acceleration is large), there is the problem that the recording and playback head, which moves in the vertical direction on the basis of the servo signals that have been prerecorded on the recording tape, becomes unable to follow those abrupt fluctuations in the position of the recording tape and ends up becoming unable to record and play back desired data signals.

Further, when servo tracking control is improved even more, the allowable amount of fluctuation in the width direction of the recording tape during travel inside the drive device—and particularly fluctuation at a high frequency (fluctuation in a short amount of time)—also becomes smaller. In other words, in high recording density recording and playback systems, it is foreseeable that, from this time forward, the size of the recording signals will become finer, the recording density will become higher, the size of the servo signals will become smaller, the recording density of the servo signals themselves will be improved, the servo tracking control system will become controlled at a high frequency, the traveling speed of the recording tape will become faster, and data signal recording and playback errors resulting from servo signal reading errors will occur even with fluctuations in the recording tape of a level that has thus far not been a problem.

Meanwhile, causing the recording tape to travel along the inner surface of an upper flange of the hub by disposing a tapered angle of 0.01 degree to 0.1 degree in the hub and making the traveling reference of the recording tape to be on the side of the hub where the outer diameter is large (here, the upper side of the hub) has been disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2004-134060, for example. That is, in JP-A No. 2004-134060, there is disclosed that, when the hub has a tapered shape, the recording tape becomes wound around the hub toward the side of the hub where the outer diameter is large.

However, recording tape has curvature (curvature in a width direction), this curvature of the recording tape affects the position where the recording tape is wound around the hub, and there are many instances where that affect is greater than the affect resulting from the hub being given a tapered shape. Consequently, when recording tape is wound around the hub described in JP-A No. 2004-134060, there is the potential for the recording tape to be taken up along the inner surface of a lower flange depending on the orientation of the curvature of the recording tape.

In other words, even when the traveling reference of the recording tape is made to be on the upper flange side, there is the potential for the recording tape to end up traveling along the lower flange side. Further, when the amount of curvature of the recording tape is large, there is the danger for the recording tape to be caused to excessively move toward one of the flanges and for the tape edge to be strongly pushed against that flange and end up sustaining damage. That problem becomes pronounced particularly when the recording tape is made thinner. Further, when the recording tape is strongly pushed too much toward one of the flanges, there is also the danger for the one-layer protrusion phenomenon to occur because of a reaction triggered by this.

Further, preventing disorderly winding of recording tape when the hub becomes deformed and the distance between the upper and lower flanges is gradually reduced in accompaniment with this deformation as the constricting force (coiling force) of the recording tape with respect to the hub increases is disclosed in JP-A No. 2002-251859, for example. However, the amount of the gradual reduction of the distance between the upper and lower flanges resulting from deformation of the hub changes also depending on the rigidity of the hub. Further, an instance where a tapered shape is imparted to the hub is not mentioned in JP-A No. 2002-251859.

Moreover, that the winding shape (winding surface) is orderly (that orderly windability is improved) when the reel is made into one where the hub diameter on one end side of the outer peripheral surface of the hub becomes smaller with respect to the hub diameter on the other end side as the recording tape is wound around the hub is disclosed in JP-A No. 2004-310827. In this instance, the tapered amount of the hub increases in accompaniment with an increase in the winding amount of the recording tape around the hub, but ordinarily there are variations in the orientation of the curvature and the amount of curvature of the recording tape, so the traveling position of the recording tape with respect to the hub fluctuates and the winding shape (winding surface) of the recording tape onto the hub fluctuates. For that reason, in this reel, there is the danger for the orderly windability of the recording tape to be impaired and for this to promote tape edge damage.

SUMMARY OF THE INVENTION

Thus, in view of the above-described circumstances, the present invention addresses obtaining a tape reel, a recording tape cartridge, a take-up reel, a pullout member and a drive device which, when recording tape has been wound around a hub, can control fluctuation of the recording tape in an axial direction of the hub, can control one-layer protrusion and disorderly winding of the recording tape that has been wound around the hub, can control problems that occur as a result of the one-layer protruding recording tape striking a flange, bending and sustaining tape edge damage when the recording tape cartridge receives a shock such as when the recording tape cartridge is dropped or the like, and can reduce servo signal reading errors and data signal recording and playback errors.

A tape reel pertaining to a first aspect of the invention is provided by a tape reel including: a hub around which recording tape is wound; and flanges disposed on both end portions of the hub, wherein the elastic modulus in a radial direction of the hub is equal to or greater than 16.0 GPa, the hub includes different radii on one end side thereof and another end side thereof, and the recording tape is wound around the hub such that the side where the radius of curvature of the curvature of the tape edge of the recording tape is small corresponds to the small radius side of the hub.

According to the first aspect of the invention, in a hub where a difference in radii is disposed on both end portions, the elastic modulus, i.e., a flexural modulus, in the radial direction of the hub is equal to or greater than 16.0 GPa, so the following actions (1) and (2) are provided, and the recording tape can be caused to move toward the flange on the small radius side of the hub and be wound around the hub because of the synergistic effects of (1) and (2). It will be noted that when the elastic modulus in the radial direction of the hub is equal to or greater than 19.2 GPa, this becomes more effective and is preferable.

(1) When tension is applied in a direction substantially perpendicular with respect to the axial line of the hub and the recording tape is wound around the hub, the recording tape moves toward the flange on the small radius side of the hub because of the imbalance in the distribution of the surface pressure acting on the recording tape, and the recording tape is wound around the hub.

(2) When the recording tape is wound around the hub such that the side where the radius of curvature of the curvature of the tape edge is small becomes the small radius side of the hub, the direction in which the recording tape moves becomes the small radius side of the hub.

Thus, fluctuation of the recording tape in the axial direction of the hub (direction perpendicular with respect to the traveling direction of the recording tape) can be controlled, disorderly winding of the recording tape can be controlled, and orderly windability can be improved. Additionally, the occurrence of a step or one-layer or plural-layer protrusion from the winding surface of the recording tape that has been wound around the hub can be controlled, and problems that occur as a result of the one-layer protruding recording tape striking a flange, bending and sustaining tape edge damage when the recording tape cartridge receives a shock such as during transport or when the recording tape cartridge is dropped or during handling can be reduced.

Further, the tape traveling position can be stabilized because the position of the recording tape can be controlled from fluctuating in the axial direction of the hub (direction perpendicular with respect to the traveling direction of the recording tape) even during travel of the recording tape inside the drive device. For this reason, servo signal reading errors and data signal recording and playback errors can be reduced even in high density recording, and a reduction of so-called position error signals and off-track can be expected.

Further, in the tape reel of the first aspect of the invention, the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape may be equal to or greater than 0.00039 and equal to or less than 0.00474.

When the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is close to 0 (in the instance of a hub having a substantially circular cylinder shape), the effect of causing the recording tape that is wound around the hub to move toward the small radius side of the hub cannot be obtained. Further, when the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is too large, there is the danger for the recording tape to be pushed excessively toward the flange surface on the small radius side of the hub and sustain tape edge damage such that so-called radiation occurs, for the recording tape to interfere with the flange during travel and further sustain tape edge damage, and in addition for phenomena that develop into defects such as cinching to occur.

For this reason, in the tape reel of the above-described configuration, the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is identified. Specifically, the ratio of the difference between the radii is in the range of 0.00039 or greater and 0.00474 or less. Here, when the amount of curvature of the recording tape is small (e.g., 0.5 mm to 2.0 mm), the recording tape functions sufficiently in this range. However, from the standpoints of the productivity of the tape reel and design freedom, even when the amount of curvature of the recording tape is large (e.g., 2.5 mm), an excellent result can be obtained as long as the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is in the range of 0.00055 or greater and 0.00400 or less.

In other words, when the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is in the range of 0.00055 or greater and 0.00400 or less, even when the radius of curvature of the curvature of the tape edge of the recording tape is small (even when the amount of curvature of the recording tape is large, such as 2.5 mm, for example), bad traveling phenomena such as tape edge damage and abnormal sounds resulting from the recording tape being excessively pushed toward the flange surface on the small radius side of the hub and interfering with the flange can be controlled. It will be noted that, although details of a measurement method will be described later, “amount of curvature” here means, using a line that interconnects both end portions of recording tape having a length of 1.0 mm as a reference line, the distance between that reference line and the center portion of the recording tape.

Further, in the tape reel of the first aspect of the invention, the width of the recording tape may be substantially 12.65 mm, and the difference between the radius on the one end side of the hub and the radius on the other end side of the hub may be equal to or greater than 5 μm and equal to or less than 60 μm.

When the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is close to 0 (in the instance of a hub having a substantially circular cylinder shape), the effect of causing the recording tape that is wound around the hub to move toward the small radius side of the hub cannot be obtained. Further, when the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is too large, there is the danger for the recording tape to be pushed excessively toward the flange surface on the small radius side of the hub and sustain tape edge damage such that so-called radiation occurs, for the recording tape to interfere with the flange during travel and further sustain tape edge damage, and in addition for phenomena that develop into defects such as cinching to occur.

For this reason, in the tape reel of the above-described configuration, when the width of the recording tape is substantially 12.65 mm, the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is equal to or greater than 5 μm and equal to or less than 60 μm. Here, when the amount of curvature of the recording tape is small (e.g., 0.5 mm to 2.0 mm), the recording tape functions sufficiently in this range. However, from the standpoints of the productivity of the tape reel and design freedom, even when the amount of curvature of the recording tape is large (e.g., 2.5 mm), an excellent result can be obtained as long as the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is in the range of 7 μm or greater and 50 μm or less.

In other words, when the width of the recording tape is substantially 12.65 mm, when the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is in the range of 7 μm or greater and 50 μm or less, even when the radius of curvature of the curvature of the tape edge of the recording tape is small (even when the amount of curvature of the recording tape is large, such as 2.5 mm, for example), bad traveling phenomena such as tape edge damage and abnormal sounds resulting from the recording tape being excessively pushed toward the flange surface on the small radius side of the hub and interfering with the flange can be controlled.

Further, in the tape reel of the above-described configuration, the absolute value of the amount of curvature of the recording tape may be equal to or greater than 0.15 mm and equal to or less than 2.5 mm.

According to the tape reel of the above-described configuration, the absolute value of the amount of curvature of the recording tape is in the range of 0.15 mm or greater and 2.5 mm or less, so bad traveling phenomena such as tape edge damage and abnormal sounds resulting from the recording tape being excessively pushed toward the flange surface on the small radius side of the hub because of large curvature and interfering with the flange can be controlled. Further, ordinarily, when the curvature is in the vicinity of 0, it is easy for disorderly winding to occur as result of the polarity of the curvature value fluctuating, and the winding surface becomes a so-called rough winding state, but disorderly winding is controlled by making the absolute value of the amount of curvature equal to or greater than 0.15 mm and combining this with the aforementioned characteristic, and the winding surface becomes closer to orderly winding.

In other words, instances where the recording tape sustains tape edge damage such that so-called radiation occurs, instances where the recording tape interferes with the flange on the small radius side of the hub during travel and further sustains tape edge damage, and in addition phenomena that develop into defects such as cinching can be prevented, and a tape traveling position that is appropriate and stable and a state where there is little disorderly winding can be achieved.

It will be noted that when the absolute value of the curvature of the recording tape is in the range of 0.5 mm or greater and 2.0 mm or less, the moving of the tape edge toward the flange becomes appropriate when the recording tape has been wound around the hub, which is more preferable. In other words, there is less fluctuation in the position of the recording tape in the axial direction of the hub during travel, disorderly winding is controlled, and the recording tape is orderly wound in a state where it is along one of the upper and lower flanges, so tape edge damage is reduced in the recording tape.

Further, in the tape reel of the first aspect of the invention, the hub may be configured to include a metal that is disposed integrally with a resin by insert molding or press-fitting.

According to the tape reel of the above-described configuration, the rigidity of the hub can be easily raised in comparison to when the hub is formed by just a resin.

Further, in the tape reel of the first aspect of the invention, the thickness of the recording tape may be equal to or less than 7.5 μm.

When the thickness of the recording tape is thick, the rigidity of the recording tape also increases, so the strength of the tape edge increases, and it becomes difficult for problems such as tape edge damage to occur with respect also to pushing against the flanges, shock, friction, and wear. On the other hand, even with recording tapes of the same width, when the thickness of the recording tape becomes thin, the distribution of stress acting in the width direction of the recording tape also changes when the same tension is applied to the recording tape and the recording tape is wound around the hub. For this reason, in the tape reel of the above-described configuration, the thickness of the recording tape that is effective for application of the present invention is identified.

Further, in the tape reel of the first aspect of the invention, the recording tape may include servo signals that become a positioning reference of a recording and playback head of a drive device, and the tape edge of the recording tape that has been wound around the hub that is on the side where the radius of an outer peripheral surface of the hub is small may serve as a servo tracking control reference during travel of the recording tape.

According to the tape reel of the above-described configuration, the tape edge of the recording tape that is wound onto the hub that moves toward one of the flanges corresponds to the tape edge that is on the side that becomes the reference of servo tracking control during travel of the recording tape, so the tape traveling position of the recording tape can be stabilized. For this reason, servo tracking errors and data signal recording and playback errors can be reduced.

Further, a recording tape cartridge pertaining to a second aspect of the invention is disposed with the tape reel of the first aspect of the invention and a case that rotatably houses the tape reel.

According to the second aspect of the invention, effects that are substantially the same as the effects based on the first aspect of the invention can be obtained. In particular, there is a trend for recording tape to be made thin in order to increase the recording capacity of the recording tape per cartridge, whereby the rigidity of the recording tape drops and the strength of the tape edge drops, but because the rate of occurrence of one-layer protrusion from the winding surface of the recording tape and the amount of that protrusion can be controlled, it is difficult for the recording tape to sustain tape edge damage even when thin recording tape is used.

Further, in the recording tape cartridge of the second aspect of the invention, the tape reel that is housed therein may be single.

According to the recording tape cartridge of the above-described aspect, the orderly windability of the recording tape can be improved in the tape reel, and fluctuation of the position of the recording tape in the axial direction of the hub (direction perpendicular with respect to the traveling direction of the recording tape) during travel can be controlled, so fluctuation of the recording tape in the axial direction of the hub (direction perpendicular with respect to the traveling direction of the recording tape) in a take-up reel of a drive device that is difficult to make highly precise can be controlled by the tape reel of the recording tape cartridge. Consequently, this becomes suitable for a one-reel recording tape cartridge for backing up data of computers for which a high recording capacity is desired. It will be noted that the reason it is difficult to manufacture a take-up reel with high precision is because the shape of the take-up reel becomes complex because the take-up reel is disposed with the function of housing a pullout member inside the take-up reel.

Further, a take-up reel of a third aspect of the invention is a take-up reel that is disposed inside a drive device and around which is wound recording tape that has been pulled out from a recording tape cartridge, the take-up reel comprising: a hub around which the recording tape is wound; and flanges disposed on both end portions of the hub, wherein the elastic modulus in a radial direction of the hub is equal to or greater than 16.0 GPa, the hub includes different radii on one end side thereof and another end side thereof, and the side where the radius of curvature of the curvature of a tape edge of the recording tape is small is wound around the small radius side of the hub.

In the take-up reel of the third aspect of the invention, effects that are substantially the same as the effects based on the first aspect of the invention can be obtained. That is, according to the third aspect of the invention, in a hub where a difference in radii is disposed on both end portions, the elastic modulus in the radial direction of the hub is equal to or greater than 16.0 GPa, so the following actions (1) and (2) are provided, and the recording tape can be caused to move toward the flange on the small radius side of the hub and be wound around the hub because of the synergistic effects of (1) and (2). It will be noted that when the elastic modulus in the radial direction of the hub is equal to or greater than 19.2 GPa, this becomes more effective and is preferable.

(1) When tension is applied in a direction substantially perpendicular with respect to the axial line of the hub and the recording tape is wound around the hub, the recording tape moves toward the flange on the small radius side of the hub because of the imbalance in the distribution of the surface pressure acting on the recording tape, and the recording tape is wound around the hub.

(2) When the recording tape is wound around the hub such that the side where the radius of curvature of the curvature of the tape edge is small becomes the small radius side of the hub, the direction in which the recording tape moves becomes the small radius side of the hub.

Thus, the position of the recording tape can be controlled from fluctuating in the axial direction of the hub (direction perpendicular with respect to the traveling direction of the recording tape) during travel of the recording tape inside the drive device, and the traveling position of the recording tape can be stabilized. Consequently, disorderly winding of the recording tape can be controlled, orderly windability can be improved, and the occurrence of a step or one-layer or plural-layer protrusion from the winding surface of the recording tape that has been wound around the hub can be controlled.

Further, servo signal reading errors and data signal recording and playback errors can be reduced resulting from the recording and playback head can be reduced even in high density recording, and a reduction of so-called position error signals and off-track can be expected. Further, tape edge damage that occurs during travel of the recording tape because of excessive contact with tape guides disposed in the drive device, the flanges of the take-up reel, and the flanges of the tape reel can be prevented.

Further, in the take-up reel of the third aspect of the invention, the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape that is wound around the hub may be equal to or greater than 0.00039 and equal to or less than 0.00474.

According to the take-up reel of the above-described configuration, effects that are substantially the same as effects resulting from tape reel having the same configuration can be obtained. That is, when the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape that is wound around the hub is close to 0 (in the instance of a hub having a substantially circular cylinder shape), the effect of causing the recording tape that is wound around the hub to move toward the small radius side of the hub cannot be obtained.

Further, when the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape that is wound around the hub is too large, there is the danger for the recording tape to be pushed excessively toward the flange surface on the small radius side of the hub and sustain tape edge damage such that so-called radiation occurs, for the recording tape to interfere with the flange during travel and further sustain tape edge damage, and in addition for phenomena that develop into defects such as cinching to occur.

For this reason, in the take-up reel of the above-described configuration, the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape that is wound around the hub is identified. Specifically, the ratio of the difference between the radii is in the range of 0.00039 or greater and 0.00474 or less. Here, when the amount of curvature of the recording tape is small (e.g., 0.5 mm to 2.0 mm), the recording tape functions sufficiently in this range. However, from the standpoints of the productivity of the tape reel and design freedom, even when the amount of curvature of the recording tape is large (e.g., 2.5 mm), an excellent result can be obtained as long as the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is in the range of 0.00055 or greater and 0.00400 or less.

In other words, when the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is in the range of 0.00055 or greater and 0.00400 or less, even when the radius of curvature of the curvature of the tape edge of the recording tape is small (even when the amount of curvature of the recording tape is large, such as 2.5 mm, for example), bad traveling phenomena such as tape edge damage and abnormal sounds resulting from the recording tape being excessively pushed toward the flange surface on the small radius side of the hub and interfering with the flange can be controlled. It will be noted that, although details of a measurement method will be described later, the “amount of curvature” mentioned here means, using a line that interconnects both end portions of recording tape having a length of 1.0 mm as a reference line, the distance between that reference line and the center portion of the recording tape.

Further, in the take-up reel of the third aspect of the invention, the width of the recording tape that is wound around the hub may be substantially 12.65 mm, and the difference between the radius on the one end side of the hub and the radius on the other end side of the hub may be equal to or greater than 5 μm and equal to or less than 60 μm.

In the take-up reel of the above-described configuration, effects that are substantially the same as effects resulting from a tape reel having the same configuration can be obtained. That is, when the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is close to 0 (in the instance of a hub having a substantially circular cylinder shape), the effect of causing the recording tape that is wound around the hub to move toward the small radius side of the hub cannot be obtained.

Further, when the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is too large, there is the danger for the recording tape that is wound around the hub to be pushed excessively toward the flange surface on the small radius side of the hub and sustain tape edge damage such that so-called radiation occurs, for the recording tape to interfere with the flange during travel and further sustain tape edge damage, and in addition for phenomena that develop into defects such as cinching to occur.

For this reason, in the take-up reel of the above-described configuration, when the width of the recording tape is substantially 12.65 mm, the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is equal to or greater than 5 μm and equal to or less than 60 μm. Here, when the amount of curvature of the recording tape is small (e.g., 0.5 mm to 2.0 mm), the recording tape functions sufficiently in this range. However, from the standpoints of the productivity of the tape reel and design freedom, even when the amount of curvature of the recording tape is large (e.g., 2.5 mm), an excellent result can be obtained as long as the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is in the range of 7 μm or greater and 50 μm or less.

In other words, when the width of the recording tape is substantially 12.65 mm, when the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is in the range of 7 μm or greater and 50 μm or less, even when the radius of curvature of the curvature of the tape edge of the recording tape is small (even when the amount of curvature of the recording tape is large, such as 2.5 mm, for example), bad traveling phenomena such as tape edge damage and abnormal sounds resulting from the recording tape being excessively pushed toward the flange surface on the small radius side of the hub and interfering with the flange can be controlled.

Further, in the take-up reel of the third aspect of the invention, the absolute value of the amount of curvature of the recording tape that is wound around the hub may be equal to or greater than 0.15 mm and equal to or less than 2.5 mm.

According to the take-up reel of the above-described configuration, effects that are substantially the same as effects resulting from a tape reel having the same configuration can be obtained. That is, the absolute value of the amount of curvature of the recording tape is in the range of 0.15 mm or greater and 2.5 mm or less, so bad traveling phenomena such as tape edge damage and abnormal sounds resulting from the recording tape being excessively pushed toward the flange surface on the small radius side of the hub because of large curvature and interfering with the flange can be controlled. Further, ordinarily, when the curvature is in the vicinity of 0, it is easy for disorderly winding to occur as result of the polarity of the curvature value fluctuating, and the winding surface becomes a so-called rough winding state, but disorderly winding is controlled by making the absolute value of the amount of curvature equal to or greater than 0.15 mm and combining this with the aforementioned characteristic, and the winding surface becomes closer to orderly winding.

In other words, instances where the recording tape sustains tape edge damage such that so-called radiation occurs, instances where the recording tape interferes with the flange on the small radius side of the hub during travel and further sustains tape edge damage, and in addition phenomena that develop into defects such as cinching can be prevented, and a tape traveling position that is appropriate and stable and a state where there is little disorderly winding can be achieved.

It will be noted that when the absolute value of the curvature of the recording tape is in the range of 0.5 mm or greater and 2.0 mm or less, the moving of the tape edge toward the flange becomes appropriate when the recording tape has been wound around the hub, which is more preferable. In other words, there is less fluctuation in the position of the recording tape in the axial direction of the hub during travel, disorderly winding is controlled, and the recording tape is orderly wound in a state where it is along one of the upper and lower flanges, so tape edge damage is reduced in the recording tape.

Further, in the take-up reel of the third aspect of the invention, the hub may be configured to include a metal that is disposed integrally with a resin by insert molding or press-fitting.

According to the take-up reel of the above-described configuration, effects that are substantially the same as effects resulting from a tape reel having the same configuration can be obtained. That is, the rigidity of the hub can be easily raised in comparison to when the hub is formed by just a resin.

Further, in the take-up reel of the third aspect of the invention, the thickness of the recording tape that is wound around the hub may be equal to or less than 7.5 μm.

According to the take-up reel of the above-described configuration, effects that are substantially the same as effects resulting from a tape reel having the same configuration can be obtained. That is, when the thickness of the recording tape is thick, the rigidity of the recording tape also increases, so the strength of the tape edge increases, and it becomes difficult for problems such as tape edge damage to occur with respect also to pushing against the flanges, shock, friction, and wear. On the other hand, even with recording tapes of the same width, when the thickness of the recording tape becomes thin, the distribution of stress acting in the width direction of the recording tape also changes when the same tension is applied to the recording tape and the recording tape is wound around the hub. For this reason, in the take-up reel of the above-described configuration, the thickness of the recording tape that is effective for application of the present invention is identified.

Further, in the take-up reel of the third aspect of the invention, the recording tape that is wound around the hub may include servo signals that become a positioning reference of a recording and playback head of a drive device, and the tape edge of the recording tape that has been wound around the hub that is on the side where the radius of an outer peripheral surface of the hub is small may serve as a servo tracking control reference during travel of the recording tape.

According to the take-up reel of the above-described configuration, effects that are substantially the same as effects resulting from a tape reel having the same configuration can be obtained. That is, the tape edge of the recording tape that is wound onto the hub that moves toward one of the flanges corresponds to the tape edge that is on the side that becomes the reference of servo tracking control during travel of the recording tape, so the tape traveling position of the recording tape can be stabilized. For this reason, servo tracking errors and data signal recording and playback errors can be reduced.

Further, a pullout member of a fourth aspect of the invention is a pullout member that pulls out recording tape from a recording tape cartridge, is housed in the hub of the take-up reel of the third aspect, and is disposed with a take-up surface that configures part of an outer peripheral surface of the hub, wherein the elastic modulus of the take-up surface is equal to or greater than 16.0 GPa, the take-up surface includes different radii on one end side thereof and another end side thereof, and the take-up surface and the outer peripheral surface of the hub become substantially even in a state where the pullout member is housed in the hub.

When recording tape is wound around the hub of the take-up reel when there is a step between the take-up surface of the pullout member and the outer peripheral surface of the hub, the potential for so-called “projection” to occur because of this step and for dropout to arise at that portion and lead to an error becomes greater. However, according to the pullout member of the above-described configuration, the radius on the one end side and the radius on the other end side of the take-up surface of the pullout member that configures part of the outer peripheral surface of the hub of the take-up reel are made different, and it is ensured that the take-up surface of the pullout member and the outer peripheral surface of the hub become substantially even in a state where the pullout member is housed in the hub, so such a step does not arise across the entire outer peripheral surface of the hub. For this reason, effects that are substantially the same as effects resulting from a take-up reel having the same configuration can be obtained.

Further, a drive device of a fifth aspect of the invention includes the take-up reel of the third aspect of the invention around which is wound recording tape that has been pulled out from a recording tape cartridge that has been loaded into the drive device.

According to the fifth aspect of the invention, in the drive device, effects that are substantially the same as effects resulting from a take-up reel having the same configuration can be obtained. That is, the position of the recording tape can be controlled from fluctuating in the axial direction of the hub during travel of the recording tape inside the drive device, and the tape traveling position can be stabilized. For this reason, servo signal reading errors and data signal recording and playback errors resulting from the recording and playback head can be reduced even in high density recording, and a reduction of so-called position error signals and off-track can be expected.

Further, tape edge damage that occurs because of excessive contact with tape guides disposed in the drive device, the flanges of the take-up reel, and the flanges of the tape reel can be prevented. In other words, instances where so-called radiation occurs because of tape edge damage, instances where the recording tape interferes with the flanges during travel and further sustains tape edge damage, and in addition phenomena that develop into defects such as cinching can be prevented, and a tape traveling position that is appropriate and stable and a state where there is little disorderly winding can be achieved.

Further, the drive device of the fifth aspect of the invention may include the pullout member of the fourth aspect of the invention.

According to the drive device of the above-described configuration, in the drive device, effects that are substantially the same as effects resulting from a pullout member having the same configuration can be obtained. That is, the radius on the one end side and the radius on the other end side of the take-up surface of the pullout member that configures part of the outer peripheral surface of the hub of the take-up reel are made different, and it is ensured that the take-up surface of the pullout member and the outer peripheral surface of the hub become substantially even in a state where the pullout member is housed in the hub, so a step does not arise across the entire outer peripheral surface of the hub. For this reason, it is difficult for “projection”, which occurs when the recording tape has been wound around the hub of the take-up reel when there is a step, to occur.

As described above, according to the present invention, when recording tape has been wound around a hub, fluctuation of the recording tape in an axial direction of the hub can be controlled, and one-layer protrusion and disorderly winding of the recording tape that has been wound around the hub can be controlled. Consequently, problems that occur as a result of the one-layer protruding recording tape striking a flange, bending and sustaining tape edge damage when the recording tape cartridge receives a shock such as when the recording tape cartridge is dropped or the like can be reduced, and the occurrence of servo signal reading errors and data signal recording and playback errors can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general perspective view of a recording tape cartridge pertaining to an embodiment of the present invention;

FIG. 2 is a general exploded perspective view of the recording tape cartridge pertaining to the embodiment of the present invention;

FIG. 3 is a general side sectional view of a reel pertaining to the embodiment of the present invention;

FIG. 4 is a general plan view of a reel hub;

FIG. 5 is a general plan view of a drive device after the recording tape cartridge has been loaded into the drive device;

FIG. 6 is a general side view of the drive device after the recording tape cartridge has been loaded into the drive device;

FIG. 7A and FIG. 7B are general perspective views showing the configuration of a pullout member of a take-up reel;

FIG. 8 is a general side view showing servo signals of recording tape;

FIG. 9A is a general side view showing a state where the recording tape is wound around the reel, and FIG. 9B is a general side view describing the action of the reel;

FIG. 10 is a general perspective view for describing a method of measuring radii of the reel;

FIG. 11 is a general perspective view showing a tape shape measuring device that measures the amount of curvature of the recording tape;

FIG. 12A and FIG. 12B are general side views describing the action of the tape shape measuring device;

FIG. 13 is a general perspective view showing an optical measuring device that is used for measuring the amount of curvature of the recording tape;

FIG. 14 is a general plan view showing a method of measuring the amount of curvature of positive curvature recording tape;

FIG. 15 is a general plan view showing negative curvature of the recording tape;

FIG. 16A is a winding form measurement chart of negative curvature recording tape, and FIG. 16B is a winding form measurement chart of positive curvature recording tape;

FIG. 17 is a general exploded sectional view of a reel where deformation of a reel hub and upper and lower flanges does not associatively act on/affect each of them;

FIG. 18 is a general side sectional view of the reel where deformation of the reel hub and the upper and lower flanges does not associatively act on/affect each of them;

FIG. 19 is a general side sectional view of a reel where deformation of a reel hub and upper and lower flanges associatively acts on/affects each of them;

FIG. 20 is a winding form measurement chart in an instance where negative curvature recording tape T is wound around a reel with a dependent structure where the material of the reel hub is PC and the difference between the radii of the reel hub is −0.003 mm;

FIG. 21 is a winding form measurement chart in an instance where positive curvature recording tape T is wound around a reel with a dependent structure where the material of the reel hub is Al and the difference between the radii of the reel hub is +0.040 mm;

FIG. 22 is a winding form measurement chart in an instance where negative curvature recording tape T is wound around a reel with an independent structure where the material of the reel hub is PC and the difference between the radii of the reel hub is +0.002 mm;

FIG. 23 is a winding form measurement chart in an instance where negative curvature recording tape T is wound around a reel with an independent structure where the material of the reel hub is Al and the difference between the radii of the reel hub is −0.043 mm; and

FIG. 24 is a winding form measurement chart when negative curvature recording tape is wound around a conventional reel.

DETAILED DESCRIPTION OF THE INVENTION

Below, the best mode for implementing the present invention will be described in detail on the basis of an embodiment shown in the drawings. For the convenience of description, in FIG. 1, arrow A represents the direction in which a recording tape cartridge 10 is loaded into a drive device 70 (see FIG. 5) and will be referred to as a front direction (front side) of the recording tape cartridge 10. Additionally, the direction of arrow B, which is orthogonal to arrow A, will be referred to as a right direction (right side). Further, the direction of arrow C represents a width direction in the present embodiment and will be referred to as a vertical direction, a height direction, and an axial direction of a reel 20 (a reel hub 22) and a take-up reel 80 (a reel hub 82).

As shown in FIG. 1 to FIG. 3, the recording tape cartridge 10 includes a substantially rectangular box-shaped case 12. The case 12 includes an upper case 14 and a lower case 16 that are made of a resin such as polycarbonate (PC). The upper case 14 is configured by a top plate 14A and a peripheral wall 14B that is disposed upright along the peripheral edge of the top plate 14A. The lower case 16 is configured by a bottom plate 16A and a peripheral wall 16B that is disposed upright along the peripheral edge of the bottom plate 16A. The case 12 is configured as a result of the upper case 14 and the lower case 16 being joined together by ultrasonic welding or screwing in a state where the peripheral wall 14B and the peripheral wall 16B have been brought into contact with each other.

Just one reel (tape reel) 20 is rotatably housed inside the case 12. The reel 20 is configured by a bottomed circular cylinder-shaped reel hub 22 that configures an axial center portion (winding core portion) of the reel 20, a lower flange 26 that is integrally molded with the lower end portion of the reel hub 22, and an upper flange 24 that is ultrasonically welded to and integrated with the upper end portion of the reel hub 22. A metal ring 22B that has a circular cylinder shape and is made of aluminium, for example, is integrally fixedly attached by insert molding to the inner peripheral surface side of a resin portion 22A that configures the reel hub 22. Additionally, a flexural modulus (elastic modulus, modulus of elasticity) E in the radial direction of the reel hub 22 is equal to or greater than 16.0 GPa and preferably equal to or greater than 19.2 GPa.

Here, as shown in FIG. 4, assuming that a represents the thickness of the resin portion 22A that configures the reel hub 22, that E_(a) represents the flexural modulus of the resin material of the resin portion 22, that b represents the thickness of the metal ring 22B that configures the reel hub 22, and that E_(b) represents the flexural modulus of the metal material of the metal ring 22B, then the flexural modulus E in the radial direction of the reel hub 22 is determined by: E=E_(a)×a/(a+b)+E_(b)×b/(a+b). It will be noted that the flexural modulus E_(b) of the metal ring 22B is equal to or greater than the flexural modulus E_(a) of the resin portion 22A.

Further, the values 16.0 GPa and 19.2 GPa are based on the results of Table 1 below. That is, the values of the flexural modulus E of example 3 and example 4 of Table 1 are lower limit values calculated assuming that variations and error are included by 5% in the values of the original flexural moduli E_(a) and E_(b). Consequently, when 5% error is removed from these values, the values become the above-described numerical values. Further, in Table 1, evaluations in regard to whether or not the winding form of recording tape T is good or bad are also shown. Here, example 1 is an instance where the reel hub 22 is formed by just the resin portion 22A, and example 2 is an instance where the reel hub 22 is formed by just the metal ring 22B.

TABLE 1 Elastic Modulus Elastic Modulus Elastic of Resin Portion of Resin Portion Modulus of Thickness a Thickness b when Thickness when Thickness Reel Hub; E Winding Example (mm) (mm) is a; Ea (GPa) is b; Eb (GPa) (GPa) Shape* 1 2.5 — 3.6 — 3.6  to □ 2 — 2.5 — 70.0 70.0 ∘ 3 2.0 0.5 3.6 70.0 16.9 □ 4 1.5 0.5 3.6 70.0 20.2 □ to ∘ 5 1.0 1.0 3.6 70.0 36.8 □ to ∘ *∘ = extremely good; □ = good;  = somewhat bad; x =P9 bad

Further, as shown in FIG. 3, the reel hub 22 (the resin portion 22A) is formed such that, when seen in a side sectional view, the radius of the outer peripheral surface of the reel hub 22 (the resin portion 22A) on the upper flange 24 side is larger than the radius of the outer peripheral surface of the reel hub 22 (the resin portion 22A) on the lower flange 26 side, and a difference ΔR between the radius of the reel hub 22 on the upper flange 24 side and the radius of the reel hub 22 on the lower flange 26 side is in the range of 5 μm to 60 μm. That is, the ratio of the difference ΔR between the radius of the reel hub 22 on the upper flange 24 side and the radius of the reel hub 22 on the lower flange 26 side is in the range of 0.00039 to 0.00474 with respect to the width of the recording tape T (here, ½ inch width, substantially 12.65 mm).

Here, a method of measuring the radii of the outer peripheral surface of the reel hub 22 will be described. As shown in FIG. 10, a chucking portion (a later-described reel gear 44) of the reel 20 that chucks with the drive device 70 is placed face down, and the reel 20 is set on an unillustrated master chucking gear (a high-precision reference gear). Then, in this state, the outer shape of the reel hub 22 is measured from its lower end portion side to its upper end portion side by a touch sensor probe 90 of a contact-type three-dimensional measuring machine.

It will be noted that, at this time, a hypothetical center (axial center) when measuring the radii of the reel hub 22 is the center (axial center) of the master chucking gear. Moreover, as for the positions of the upper end portion and the lower end portion of the measurement position, because the touch sensor probe 90, which has a diameter of 1 mm, is used, the center position thereof is set to be in the range of 0.7 mm to 1.0 mm from the upper end portion and the lower end portion of the reel hub 22 during measurement so as to not interfere with the upper flange 24 or the lower flange 26. Additionally, the measurement points of the touch sensor probe 90 are set in substantially equidistant intervals such that the number of measurement points is at least ten in total. This measurement is similarly performed at six places every 60 degrees.

From this result, the difference ΔR between the radius of the reel hub 22 on the upper flange 24 side and the radius of the reel hub 22 on the lower flange 26 side is calculated thusly: ΔR=ΔRmax−(ΔRmax−ΔRmin)/2=(ΔRmax+ΔRmin)/2. It will be noted that ΔRmax is a maximum value of ΔR1 to ΔR6 and that ΔRmin is a minimum value of ΔR1 to ΔR6. Further, ΔR1 to ΔR6 are radius values (n=1 to 6) equal to the radius value of the large radius side (the upper flange 24 side) of the reel hub 22 minus the small radius side (the lower flange 26 side) of the reel hub 22 at positions of six places every 60 degrees.

Further, because it suffices as long as the radii of the reel hub 22 are different between the upper flange 24 side and the lower flange 26 side in the outer shape of the reel hub 22, the outer peripheral surface of the reel hub 22 does not have to have a tapered shape where its upper side and its lower side are interconnected by a straight line when seen from the side. In other words, it is alright if there are fine concavo-convexities in the outer peripheral surface of the reel hub 22, and the outer peripheral surface of the reel hub 22 may have a shape where its upper side and its lower side are interconnected by a curved line when seen from the side. Moreover, the outer peripheral surface of the reel hub 22 may be curved when seen from the side, or part of the outer peripheral surface of the reel hub 22 may be parallel to the axial line of the reel hub 22.

Recording tape T such as magnetic tape serving as an information recording and playback medium is wound around the outer peripheral surface of the reel hub 22 of the reel 20 with a predetermined coiling force (tension) F (e.g., F=0.588 N to 0.980 N), and the fluctuation width in the width direction of the recording tape T that has been wound around the reel hub 22 is controlled by the upper flange 24 and the lower flange 26. It will be noted that the mutually opposing surfaces of the upper flange 24 and the lower flange 26 are formed as tapered surfaces 24A and 26A (see FIG. 3) where the distance between the flanges gradually increases toward the outer side (outer peripheral edge side). Further, in order to increase the recording capacity of the recording tape T, the thickness of the recording tape T is equal to or less than 7.5 μm and preferably equal to or less than 6.9 μm.

Further, ordinarily the recording tape T curves in its width direction (in the upper direction or the lower direction). In the present embodiment, when the recording tape T is seen with its upper edge T_(A) facing up, curvature where the recording tape T curves upward will be referred to as negative curvature, and curvature where the recording tape T curves downward will be referred to as positive curvature. Consequently, the recording tape T shown in FIG. 14 is positive curvature recording tape T because its upper edge T_(A) curves upward, and the recording tape T shown in FIG. 15 is negative curvature recording tape T because its upper edge T_(A) curves upward. In the reel 20 of the present embodiment, as described later, positive curvature recording tape T is wound around the reel hub 22, and the amount of curvature ΔD of the positive curvature recording tape T is in the range of 0.15 mm to 2.5 mm.

Here, “amount of curvature ΔD” means, using a line that interconnects both end portions of recording tape T that has a length of 1.0 mm as a reference line, the distance between that reference line and the center portion of the recording tape T. Next, a method of measuring the amount of curvature ΔD of the recording tape T will be described. In FIG. 11, there is shown a tape shape measuring device 100. A substantially rectangular parallelepiped-shaped electrostatic attraction base 102 is disposed in the tape shape measuring device 100, and a guide member 104 is disposed on the upper portion of the electrostatic attraction base 102.

As shown in FIG. 12A and FIG. 12B, the guide member 104 is configured so as to be horizontally movable over the upper portion of the electrostatic attraction base 102 and along the longitudinal direction of the electrostatic attraction base 102 in a state where a clearance is disposed between the guide member 104 and the upper surface (an attraction surface 102A) of the electrostatic attraction base 102. The recording tape T, which has been precut to a length of the prescribed 1 m to which leeway has been added to both ends, is placed on the attraction surface 102A of the electrostatic attraction base 102 so as to cover the upper surface of the guide member 104. Then, both end sides of the recording tape T are freed in a state where there is leeway in the length, and air is blown onto the recording tape T by a nozzle 108.

Then, with the air being blown onto the recording tape T, the guide member 104 and the nozzle 108 slide (move) at a predetermined speed along the attraction surface 102A. Thus, the recording tape T separates from the top of the attraction surface 102A and is again guided onto the attraction surface 102A in a state where excess force has been removed.

Further, as shown in FIG. 13, plural electrode pairs 110 are disposed along the longitudinal direction in the electrostatic attraction base 102. As the recording tape T is guided to the attraction surface 102A, switches of the electrode pairs 110 corresponding to the recording tape T that has been guided on the attraction surface 102A are sequentially actuated, and the attraction surface 102A sequentially charges the recording tape T in correspondence to the guiding of the recording tape T. Thus, the recording tape T carries electrostatic electricity (an electrical charge) and is sequentially attracted to the attraction surface 102A by that electrostatic attraction.

Then, the air blown from the nozzle 108 pushes the attracted recording tape T with a predetermined pressure. In this manner, when the recording tape T is pushed with the predetermined pressure, air present between the recording tape T and the attraction surface 102A is pushed out in accompaniment with the attraction surface 102A and the undersurface of the recording tape T. Consequently, the recording tape T can excellently be brought into tight contact with the attraction surface 102A.

Next, the shape of the recording tape T attracted to the attraction surface 102A is measured by an optical measuring device 112. Transparent portions 116 through which laser light L emitted from a laser generator 114 of the optical measuring device 112 is passable are disposed in the electrostatic attraction base 102. In a state where the recording tape T is attracted to the attraction surface 102A, the transparent portions 16 are irradiated with the laser light L, and the laser light L transmitted through the transparent portions 16 is received by a laser optical receiver 118 disposed below the electrostatic attraction base 102. Thus, the position of the edge of the recording tape T becomes measurable.

Specifically, as shown in FIG. 14, the laser light L, which is band-like in the width direction, is emitted from the laser generator 114 disposed on the upper side of measurement points A, B and C such that the laser light L straddles a reference line AC that interconnects the measurement point A and the measurement point C. Then, the laser light L that has been transmitted through the transparent portions 116 is received by the laser optical receiver 118 disposed below the electrostatic attraction base 102—that is, on the lower side of the measurement points A, B and C. At this time, when the recording tape T is curved, the received amount of the laser light L that is band-like in the width direction (the length in the width direction of the laser light L that has been transmitted) becomes smaller.

Next, the length in the width direction of the laser light L that has been transmitted is measured by the laser optical receiver 118 to determine the positions of the measurement points A, B and C (the position of the upper edge T_(A)). Then, the distance between the reference line AC and the measurement point B—that is, an amount of displacement (ΔD)—is calculated on the basis of the positions of the measurement points A, B and C, and the value that has been calculated becomes the amount of curvature at the measurement point B. Here, that the length of the reference line AC is 1.0 m is prescribed in JIS X6175.

Then, as shown in FIG. 14, it is regarded that the polarity of the recording tape T is positive curvature in an instance where the side where the radius of curvature of the curvature of the tape edge of the recording tape T is small is on the lower side that is shown—that is, an instance where the reference line AC is covered by the recording tape T—and, as shown in FIG. 15 (FIG. 15 is a diagram where FIG. 14 has been simplified), it is regarded that the polarity of the recording tape T is negative curvature in an instance where the side where the radius of curvature of the curvature of the tape edge of the recording tape T is on the upper side that is shown—that is, an instance where a clearance δ arises between the reference line AC and the upper side of the tape edge of the recording tape T (the so-called upper edge T_(A)). It will be noted that in a state where the recording tape T has been wound around the reel hub 22, this upper edge T_(A) side is on the upper flange 24 side of the reel hub 22.

As shown in FIG. 2, a reel gear 44 (see FIG. 3) is annularly formed on the undersurface of a bottom wall 28 of the lower flange 26, and a gear opening 40 for exposing the reel gear 44 to the outside is disposed in the center portion of the lower case 16. The reel gear 44 exposed from the gear opening 40 meshes with, and is driven to rotate by, a drive gear (not shown) of the drive device 70 (see FIG. 5), whereby the reel 20 is made capable of relative rotation with respect to the case 12 inside the case 12.

Further, an annular reel plate 46 (see FIG. 3) comprising a magnetic material is fixedly attached, by insert molding or the like, to the undersurface of the bottom wall 28 on the radial direction inner side of the reel gear 44. The reel plate 46 is configured to be attracted to and held by the magnetic force of an annular magnet (not shown) disposed in the drive device 70. Moreover, as shown in FIG. 2, the reel 20 is held, such that it does not rattle, by a free play limiting wall 42 that is partially disposed on, so as to project from, the inner surfaces of the upper case 14 and the lower case 16 and which serves as an inner wall on a circular locus coaxial with the gear opening 40.

Further, as shown in FIG. 1 and FIG. 2, an opening 18 for allowing the recording tape T wound onto the reel 20 to be pulled out is formed in a right wall 12B of the case 12. A leader pin 30 that is pulled out by, while being locked to (gripped), a leader block 85 (see FIG. 7A) that is a pullout member of the drive device 70 is fixedly attached to a free end portion of the recording tape T pulled out from the opening 18. Annular grooves 32 are formed in both end portions of the leader pin 30 that project from the width direction edges of the recording tape T, and the annular grooves 32 are locked by hooks 85A of the leader block 85 (see FIG. 7B).

Further, a pair of upper and lower pin holding portions 36 that position and hold the leader pin 30 inside the case 12 are disposed inside the opening 18 in the case 12—that is, in the inner surface of the top plate 14A of the upper case 14 and in the inner surface of the bottom plate 16A of the lower case 16. The pin holding portions 36 have substantially semicircular shapes whose sides in the direction in which the recording tape T is pulled out are open, and both end portions 34 of the leader pin 30 in an upright state are capable of entering and exiting the pin holding portions 36 from the open sides thereof.

Further, a plate spring 38 is fixedly disposed in the vicinity of the pin holding portions 36. Two-pronged distal end portions of the plate spring 38 respectively engage with both the upper and lower end portions 34 of the leader pin 30 and hold the leader pin 30 in the pin holding portions 36. It will be noted that when the leader pin 30 enters and exits the pin holding portions 36, the distal end portions of the plate spring 38 appropriately elastically deform to allow movement of the leader pin 30.

Further, the opening 18 is opened and closed by a door 50. The door 50 is formed in a substantially rectangular plate-like shape of a size capable of blocking the opening 18, and groove portions 64 that allow the upper and lower end portions of the door 50 to slidably fit therein are formed in the top plate 14A and the bottom plate 16A inside the opening 18 so that the door 50 can move along the right wall 12B of the case 12.

Further, a shaft 52 is disposed on, so as to project from, the center of the rear end portion of the door 50, and a coil spring 58 is fitted over the shaft 52. Additionally, an enlarged portion 54 that prevents the coil spring 58 from coming off is formed on the rear end of the shaft 52. Further, a support table 60 including a locking portion 62 that locks the rear end of the coil spring 58 fitted over the shaft 52 is disposed on, so as to project from, the lower case 16.

Consequently, the shaft 52 is slidably supported on the support table 60 and the rear end of the coil spring 58 is locked by the locking portion 62, whereby the door 50 is always biased by the biasing force of the coil spring 58 in the direction in which the door 50 blocks the opening 18. It will be noted that it is preferable to further projectingly dispose, on the rear side of the support table 60, a support table 66 that supports the shaft 52 when the opening 18 is open.

Further, a tongue portion 56 for opening and closing the door 50 is disposed on the front end portion of the door 50 so as to project outward. The tongue portion 56 is configured to engage with an opening/closing member (not shown) of the drive device 70 in accompaniment with the loading of the recording tape cartridge 10 into the drive device 70. Thus, the door 50 is opened counter to the biasing force of the coil spring 58.

Next, an example of the drive device 70 into which the recording tape cartridge 10 is loaded will be described. As shown in FIG. 5 to FIG. 7B, the drive device 70 includes a take-up reel 80 that houses the leader block 85, which grips and pulls out the leader pin 30 from the recording tape cartridge 10, and around which take-up reel 80 is wound the recording tape T that has been pulled out via the leader pin 30.

Additionally, the take-up reel 80 has substantially the same configuration as that of the reel 20. That is, the take-up reel 80 includes a bottomed circular cylinder-shaped reel hub 82 that configures an axial center portion (winding core portion) of the take-up reel 80, a lower flange 86 that is integrally molded with the lower end portion of the reel hub 82, and an upper flange 84 that is screwed (fixedly attached) to and integrally configured with the upper end portion of the reel hub 82 via a pressing plate (not shown) made of metal. A metal ring 82B that has a circular cylinder shape and is made of aluminium, for example, is integrally fixedly attached by insert molding to the inner peripheral surface side of a resin portion 82A that configures the reel hub 82.

Additionally, a flexural modulus E in the radial direction of the reel hub 82 is equal to or greater than 16.0 GPa and preferably equal to or greater than 19.2 GPa. Further, the reel hub 82 is formed such that, when seen in a side sectional view, the radius of the outer peripheral surface of the reel hub 82 on the upper flange 84 side is larger than the radius of the outer peripheral surface of the reel hub 82 on the lower flange 86 side, and a difference ΔR between the radius of the reel hub 82 on the upper flange 84 side and the radius of the reel hub 82 on the lower flange 86 side is in the range of 5 μm to 60 μm (the ratio of the difference ΔR between the radius of the reel hub 82 on the upper flange 84 side and the radius of the reel hub 82 on the lower flange 86 side is in the range of 0.00039 to 0.00474 with respect to the width of the recording tape T). These are the same as the reel 20.

Further, because it suffices as long as the radii of the reel hub 82 are different between the upper flange 84 side and the lower flange 86 side in the outer shape of the reel hub 82, the outer peripheral surface of the reel hub 82 does not have to have a tapered shape where its upper side and its lower side are interconnected by a straight line when seen in a side view. In other words, it is alright if there are fine concavo-convexities in the outer peripheral surface of the reel hub 82, and the outer peripheral surface of the reel hub 82 may have a shape where its upper side and its lower side are interconnected by a curved line when seen from the side. Moreover, the outer peripheral surface of the reel hub 82 may be curved when seen from the side, or part of the outer peripheral surface of the reel hub 82 may be parallel to the axial line of the reel hub 82.

Moreover, the mutually opposing surfaces of the upper flange 84 and the lower flange 86 are formed as tapered surfaces 84A and 86A (see FIG. 6) where the distance between the flanges gradually increases toward the outer side (outer peripheral edge side), and the fluctuation width in the width direction of the recording tape T that has been wound around the reel hub 82 is controlled by the upper flange 84 and the lower flange 86. These are also the same as the reel 20.

Incidentally, as shown in FIG. 7A and FIG. 7B, the leader block 85 that grips the leader pin 30 and has an arcuate shape when seen in plan view is disposed in the reel hub 82 of the take-up reel 80 such that the leader block 85 is capable of being attached to and detached from (capable of being housed in) the reel hub 82. Part of the metal ring 82B is exposed to a flat surface 83 of the reel hub 82 that is exposed in a state where the leader block 85 has been removed from the reel hub 82, and a slit portion 81 that allows leader tape 87 that is attached to one end portion of the leader block 85 is formed in the height direction of the metal ring 82B (the axial direction of the reel hub 82).

Additionally, the leader block 85 is attached to the reel hub 82 in a state where a flat surface 85B of the leader block 85 faces the flat surface 83 of the reel hub 82, and the leader block 85 configures part of the outer peripheral surface (take-up surface) of the reel hub 82 in this state. Here, it is necessary for a circular arc-shaped surface (take-up surface) 85C of the leader block 85 to be given the same shape as that of the outer peripheral surface of the reel hub 82.

That is, the leader block 85 configures part of the take-up surface of the reel hub 82 in a state where the leader block 85 is attached to the reel hub 82, so when the recording tape T is wound around the reel hub 82 when there is a step between the circular arc-shaped surface 85 of the leader block 85 and the outer peripheral surface of the reel hub 82, the potential for so-called “projection” to occur because of this step and for dropout to arise at that portion and lead to an error becomes greater.

For that reason, the circular arc-shaped surface 85C of the leader block 85 is given the same shape as that of the outer peripheral surface of the reel hub 82, whereby it is ensured that the circular arc-shaped surface 85C of the leader block 85 and the outer peripheral surface of the reel hub 82 become substantially even in a state where the leader block 85 is attached to the reel hub 82 and that a step does not arise across the entire outer peripheral surface of the reel hub 82.

Further, plural tape guides 72, 74, 76 and 78 are disposed in the drive device 70 (here, four tape guides are disposed). The tape guides 72, 74, 76 and 78 respectively include circular cylinder-shaped hubs 72C, 74C, 76C and 78C, flanges 72A, 74A, 76A and 78A that are formed on the upper sides of the hubs 72C, 74C, 76C and 78C, and flanges 72B, 74B, 76B and 78B that are formed on the lower sides of the hubs 72C, 74C, 76C and 78C. The tape guides 72, 74, 76 and 78 control the position in the vertical direction (the axial direction of the hubs 72C, 74C, 76C and 78C) of the recording tape T that has been pulled out from the recording tape cartridge 10 loaded inside the drive device 70. Additionally, a recording and playback head 88 is disposed between the tape guide 74 and the tape guide 76, and recording and playback of information with respect to the recording tape T is performed by the recording and playback head 88.

Next, the action of the recording tape cartridge 10 and the drive device 70 of the above-described configurations will be described. In the recording tape cartridge 10 of the above-described configuration, when the recording tape cartridge 10 is not in use (during storage or during transport) when the recording tape cartridge 10 is not loaded in the drive device 70, the opening 18 is blocked by the door 50. Then, when the recording tape T is to be used, the recording tape cartridge 10 is loaded front wall 12A first inside the drive device 70 along the direction of arrow A.

Then, the recording tape cartridge 10 is inserted into an unillustrated bucket, and the opening/closing member disposed in the bucket (the drive device 70) engages with the tongue portion 56 of the door 50. Then, in this state, when the recording tape cartridge 10 moves further in the direction of arrow A, the opening/closing member causes the tongue portion 56 to move relatively rearward counter to the biasing force of the coil spring 58. Then, the door 50 on which the tongue portion 56 is projectingly disposed slides rearward inside the groove portions 64 along the right wall 12B to open the opening 18.

In this manner, when the recording tape cartridge 10 is loaded a predetermined depth in the drive device 70 (the bucket) and the opening 18 is completely opened, the bucket housing the recording tape cartridge 10 is lowered a predetermined height, and a positioning member (not shown) of the drive device 70 is relatively inserted into a positioning hole portion (not shown) formed in the lower case 16. Thus, the recording tape cartridge 10 is accurately positioned in a predetermined position inside the drive device 70, and further sliding of the door 50 (movement rearward) is controlled.

Further, because of the downward movement of the recording tape cartridge 10 (the bucket), the drive gear relatively enters the gear opening 40, engages with the reel gear 44, and causes the reel 20 to rise to a predetermined height (see FIG. 6). Then, in a state where the drive gear and the reel gear 44 are completely meshed, the reel plate 46 is attracted to and held by the magnetic force of the annular magnet disposed inside the drive gear, whereby the reel 20 is placed in an unlocked state where it becomes relatively rotatable with respect to the case 12 inside the case 12 while the meshing of the reel gear 44 with respect to the drive gear is maintained.

Meanwhile, the leader block 85 (see FIG. 7A) disposed in the drive device 70 enters the case 12 through the opened opening 18 and grips and pulls out the leader pin 30 positioned and held in the pin holding portions 36. It will be noted that, at this time, the hooks 85A of the leader block 85 can be reliably caused to lock into the annular grooves 32 in the leader pin 30 because the recording tape cartridge 10 is accurately positioned inside the drive device 70. Further, the reel 20 can rotate in accompaniment with the pulling-out of the leader pin 30 because the reel 20 has been released from its rotationally locked state.

In this manner, as shown in FIG. 7B, the take-up reel 80 rotates, whereby the leader block 85 that holds the leader pin 30 that has been pulled out from the opening 18 is attached to (housed in) the reel hub 82 so as to configure part of the reel hub 82. Then, the take-up reel 80 and the reel 20 are driven to rotate synchronously, whereby the recording tape T is sequentially pulled out from the case 12 while being taken up on the take-up reel 80.

Further, at this time, as shown in FIG. 5 and FIG. 6, the recording tape T that has been pulled out from the inside of the case 12 slidingly contacts the tape guide 72 disposed most proximate to the recording tape cartridge 10. The tape guide 72 is supported such that it may freely rotate and is attached such that its height position is, with respect to the width direction (height direction) of the reel hub 22, either in a central position or a position that is eccentrically located either higher or lower than the central position. Here, the tape guide 72 is attached such that its center position in its width direction (height direction) is eccentrically located in a lower position than the center position in the width direction (height direction) of the tape reel 22, for example.

Consequently, the recording tape T slidingly contacting the tape guide 72 travels in a state where its upper edge is controlled by the upper flange 72A of the tape guide 72. Next, the recording tape T slidingly contacts the tape guide 74, which is supported such that it may freely rotate. The tape guide 74 is attached such that its center position in its width direction (height direction) is eccentrically located in a higher position than the center position in the width direction (height direction) of the tape reel 22, and the lower edge of the recording tape T is controlled by the lower flange 74B of the tape guide 74.

Next, the recording tape T, whose position is controlled by the tape guide 74, slidingly contacts the tape guide 76, which is supported such that it may freely rotate. It will be noted that the recording tape T slidingly contacts the recording and playback head 88 before it slidingly contacts the tape guide 76. Conversely from the tape guide 74, that is, similar to the tape guide 72, the tape guide 76 is attached such that its center position in its width direction (height direction) is eccentrically located in a lower position than the center position in the width direction (height direction) of the reel hub 22, and the upper edge of the recording tape T is controlled by the upper flange 76A of the tape guide 76.

Finally, the recording tape T, whose position is controlled by the tape guide 76, slidingly contacts the tape guide 78, which is supported such that it may freely rotate. Similar to the tape guide 74, the tape guide 78 is attached such that its center position in its width direction (height direction) is eccentrically located in a higher position than the center position in the width direction (height direction) of the reel hub 22, and the lower edge of the recording tape T is controlled by the lower flange 78B of the tape guide 78.

In this manner, when the height positions (positions in the width direction) of the tape guides 72, 74, 76 and 78 inside the drive device 70 are mutually different along the tape path of the recording tape T, there is the advantage that control of the position in the width direction (vertical direction) of the recording tape T can be performed appropriately. It will be noted that, because each of the tape guides 72, 74, 76 and 78 is supported such that it may freely rotate, there are few instances where the edges of the recording tape T sustain damage due to the tape guides 72, 74, 76 and 78.

In this manner, when the leader pin 30 becomes housed in the reel hub 82 of the take-up reel 80 while the position of the recording tape T in its width direction (vertical direction) is controlled by the tape guides 72, 74, 76 and 78, the take-up reel 80 and the reel 20 are synchronously driven to rotate, whereby the recording tape T is sequentially pulled out from the case 12 while being taken up on the take-up reel 80, and recording and playback of information is performed by the recording and playback head 88 disposed between the predetermined tape guides 74 and 76.

Here, the recording and playback head 88 is supported such that it is movable in the vertical direction (height direction) by an unillustrated actuator, for example, follows servo signals S (see FIG. 8) disposed on the recording tape T, and is configured to be movable in the width direction of the recording tape T (the axial direction of the reel hubs 22 and 82).

As shown in FIG. 8, for example, the servo signals S are configured in groups. Here, four (or five, etc.) servo signals S arranged parallel to each other form one pattern P, and two mutually adjacent patterns P form one group of servo signals S (refer to the circled portion in FIG. 8). Each of these groups of servo signals S has a substantial truncated V-shape. The groups of servo signals S formed in substantial truncated V-shapes are disposed in one row each in the vicinities of the upper edge and the lower edge of the recording tape T such that the wider sides of the inverted substantial truncated V-shapes face outward.

According to such servo signals S, when the detection time (distance) between two groups of the servo signals S (indicated by W in FIG. 8) becomes long, it is understood that the position of the traveling recording tape T has shifted either up or down with respect to the recording and playback head 88, whereby the position in the vertical direction (height direction) of the recording and playback head 88 can be adjusted.

In the reel 20 and the take-up reel 80 of the present embodiment, the elastic moduli E in the radial direction of the reel hubs 22 and 82 are both equal to or greater than 16.0 GPa, the radii of the outer peripheral surfaces of the reel hubs 22 and 82 on the side of the upper flanges 24 and 84 are larger than the radii of the outer peripheral surfaces of the reel hubs 22 and 82 on the side of the lower flanges 26 and 86, and positive curvature recording tape T is wound around the reel hubs 22 and 82. Thus, as described later, the recording tape T appropriately moves toward the end portions on the side of the lower flanges 26 and 86 of the reel hubs 22 and 82, and the traveling reference of the recording tape T is made to be on the side of the lower flanges 26 and 86 (small radius side) of the reel hubs 22 and 82.

In other words, fluctuation in the position of the recording tape T in the vertical direction (the axial direction of the reel 20 and the take-up reel 80) is appropriately controlled, and the traveling position of the recording tape T can be stabilized. Consequently, by using the edge of the recording tape T on the side of the lower flanges 26 and 86 as a servo tracking control reference during travel of the recording tape T, the occurrence of servo signal S reading errors (servo tracking errors) and data signal (information) recording and playback errors can be reduced.

In this manner, the recording tape T, with respect to which recording and playback of information has ended without error as a result of the recording tape T slidingly contacting the recording and playback head 88 while the height position (position in the width direction) of the recording tape T is controlled by the tape guides 72, 74, 76 and 78, the shapes of the reel hubs 22 and 82 of the reel 20 and the take-up reel 80 and the orientation of the curvature of the recording tape T, is rewound onto the reel 20 as a result of the drive gear and the take-up reel 80 reversely rotating.

When the recording tape T is completely rewound onto the reel 20 and the leader pin 30 is held in the pin holding portions 36, the bucket housing the recording tape cartridge 10 rises a predetermined height, the positioning member is pulled out from the positioning hole portion, the drive gear is pulled out from the gear opening 40, and the drive gear disengages from the reel gear 44. Then, the reel 20 is lowered to its original height position inside the recording tape cartridge 10.

Thereafter, the recording tape cartridge 10 is moved in the opposite direction of the direction of arrow A by an unillustrated ejecting mechanism, and in accompaniment with this movement, the door 50 is slid by the biasing force of the coil spring 58 in the direction in which the door 50 blocks the opening 18 to completely block the opening 18 (the door 50 returns to its initial state). In this manner, the recording tape cartridge 10 whose opening 18 has been blocked is completely ejected from the inside of the drive device 70 (the bucket).

Next, the action and effects of the above-described reel 20 and take-up reel 80 will be described in greater detail. It will be noted that, because the action and effects of the take-up reel 80 are substantially the same as the action and effects of the reel 20, the reel 20 will be mainly described below and description of the take-up reel 80 will be appropriately omitted.

As shown in FIG. 3, the reel 20 pertaining to the present embodiment is configured as a result of the reel hub 22 and the lower flange 26 being integrally molded, the upper flange 24 being welded to and integrated with the reel hub 22, and the metal ring 22B made of aluminium or the like being integrally fixedly adhered by inserted molding to the inner peripheral surface side of the resin portion 22A of the reel hub 22. Additionally, the flexural modulus E in the radial direction of the reel hub 22 is equal to or greater than 16.0 GPa and preferably equal to or greater than 19.2 GPa.

Further, the radius of the outer peripheral surface of the reel hub 22 (the resin portion 22A) on the upper flange 24 side is larger than the radius of the outer peripheral surface of the reel hub 22 (the resin portion 22A) on the lower flange 26 side, and the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the lower flange 26 side of the reel hub 22 is in the range of 5 μm to 60 μm (the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is 0.00039 to 0.00474).

Here, usually the recording tape T is wound around the reel hub such that the recording tape T moves toward the upper flange 24 side or the lower flange side 26 because of differences in the polarity of the curvature of the recording tape T. In FIG. 16B and FIG. 16B, there are shown examples of winding form measurement charts where negative curvature recording tape T and positive curvature recording tape T are wound around a conventional reel hub (not shown) where the radius of the outer peripheral surface is substantially the same on the upper flange 24 side and the lower flange 26 side. It will be noted that fluctuation of the winding surface midway is omitted in FIG. 16 and FIG. 16B.

As shown in FIG. 16A, when the polarity representing the orientation of the curvature of the recording tape T is in a negative direction (negative curvature), the recording tape T moves toward the upper flange 24 side along the axial direction of the reel hub as the recording tape T is wound around the reel hub. Additionally, as shown in FIG. 16B, when the polarity representing the orientation of the curvature of the recording tape T is in a positive direction (positive curvature), the recording tape T moves toward the lower flange 26 side along the axial direction of the reel hub as the recording tape T is wound around the reel hub. In this manner, the direction in which the recording tape T moves changes depending on differences in the polarity of the curvature of the recording tape T.

Consequently, as shown in FIG. 9A and FIG. 9B, the polarity representing the orientation of the curvature of the tape edge of the recording tape T wound around the reel hub 22 of the reel 20 pertaining to the present embodiment is in a positive direction (positive curvature). In other words, the recording tape T is wound around the reel hub 22 such that the side where the radius of curvature of the curvature of the tape edge of the recording tape T is small becomes the lower flange 26 side. Thus, the recording tape T can be made to appropriately move toward the lower flange 26 side, the winding form (winding shape) of the recording tape T can be made excellent, and the traveling reference of the recording tape T can be made to be on the lower flange 26 side (small radius side) of the reel hub 22.

Here, as comparative examples compared with the reel 20 pertaining to the present embodiment, a reel 120 shown in FIG. 17 and FIG. 18 and a reel 220 shown in FIG. 19 will be described. First, the reel 120 shown in FIG. 17 and FIG. 18 will be described, but in each of the reels 120 and 220, similar to the reel 20, the radii of outer peripheral surfaces of reel hubs 122 and 222 on the side of upper flanges 124 and 224 are larger than the radii of the outer peripheral surfaces of the reel hubs 122 and 222 on the side of lower flanges 126 and 226.

That is, the difference ΔR between the radius on the upper flanges 124 and 224 side of the reel hubs 122 and 222 and the radius on the lower flanges 126 and 226 side of the reel hubs 122 and 222 is in the range of 5 μm to 60 μm (the ratio of the difference ΔR between the radius on the upper flanges 124 and 224 side of the reel hubs 122 and 222 and the radius on the lower flanges 126 and 226 side of the reel hubs 122 and 222 with respect to the width of the recording tape T is 0.00039 to 0.00474).

The reel 120 shown in FIG. 17 and FIG. 18 includes a circular cylinder-shaped reel hub 122 that configures an axial center portion (winding core portion) of the reel 120, an annular upper flange 124 that is disposed on the upper end portion of the reel hub 122, and a disc-shaped lower flange 126 that is disposed on the lower end portion of the reel hub 122. The reel hub 122 and the upper and lower flanges 124 and 126 are separately molded such that they are mutually independent.

That is, a circular cylinder-shaped upper circular cylinder portion 124A is disposed vertically on the inner edge portion and on a concentric circumference of the upper flange 124, and a circular cylinder-shaped lower circular cylinder portion 126A that has substantially the same diameter as that of the upper circular cylinder portion 124A is disposed upright on the upper surface of the lower flange 126. Additionally, the reel hub 122 has an inner diameter dimension that is larger than outer diameter dimensions of the lower circular cylinder portion 126A and the upper circular cylinder portion 124A, and the reel hub 122 is capable of being fitted over the lower circular cylinder portion 126A and the upper circular cylinder portion 124A in a state of non-contact (in a state where a predetermined clearance is formed between the outer peripheral surfaces of the lower circular cylinder portion 126A and the upper circular cylinder portion 124A and the inner peripheral surface of the reel hub 122).

Further, the length of the reel hub 122 is substantially the same as the sum of the length of the lower circular cylinder portion 126A and the length of the upper circular cylinder portion 124A, and a welding rib 125 whose cross section is triangular is disposed on, so as to project from, the center portion of the upper end surface of the lower circular cylinder portion 126A (or the center portion of the lower end surface of the upper circular cylinder portion 124A) along the circumferential direction thereof. Moreover, ribs (engaging portions) 123 of a predetermined length (including width) and a predetermined height are disposed coaxially and continuously in at least three places in substantially equidistant intervals on, so as to project from, the outer side of the lower circular cylinder portion 126A of the lower flange 126, and engagement grooves (engaged portions) 122A of a predetermined length (including width) and a predetermined depth into which the ribs 123 are capable of being inserted in a state where there is virtually no clearance in the circumferential direction of the reel hub 122 but where there is a predetermined clearance in the radial direction of the reel hub 122 are formed in the center portion of the lower end surface of the reel hub 122 in at least three places continuously along in the circumferential direction of the reel hub 122 and in substantially the same intervals as those of the opposing ribs 123.

Consequently, the reel hub 122 is fitted over the lower circular cylinder portion 126A of the lower flange 126, the engagement grooves 122A in the reel hub 122 are caused to engaged with the ribs 123 of the lower flange 126, the reel hub 122 is positioned (centered) with respect to the lower flange 126, the upper circular cylinder portion 124A of the upper flange 124 is inserted inside the reel hub 122, the lower end surface of the upper circular cylinder portion 124A is brought into contact with the upper end surface of the lower circular cylinder portion 126A, and an ultrasonic wave is oscillated to melt the welding rib 125 in this state, whereby the upper circular cylinder portion 124A is welded to the lower circular cylinder portion 126A.

In other words, the upper flange 124, the lower flange 126 and the reel hub 122 are thus assembled in a state where they are coaxially disposed (in a state where coaxiality is maintained), the reel hub 122 is held by the upper and lower flanges 124 and 126, and the reel hub 122 is made incapable of relative rotation with respect to the upper and lower flanges 124 and 126 (made incapable of moving relatively in the circumferential direction). Additionally, a predetermined clearance is formed in the radial direction of the reel hub 122 between the engagement grooves 122A and the ribs 123, and a predetermined clearance is formed between the outer peripheral surfaces of the lower circular cylinder portion 126A and the upper circular cylinder portion 124A and the inner peripheral surface of the reel hub 122 (such that they do not contact).

For that reason, the reel hub 122 and the upper and lower flanges 124 and 126 are not mutually affected by deformation. That is, the reel hub 122 and the upper and lower flanges 124 and 126 are mutually independent, and even if the reel hub 122 were to become deformed by the coiling force F of the recording tape T, for example, there is no danger that the upper flange 124 or the lower flange 126 will be affected by that deformation and become deformed. Consequently, in the reel 120 of this configuration, the recording tape T can be caused to move toward the lower flange 126 side that is the small radius side of the reel hub 122 and be wound around the reel hub 122 because of the following synergistic effects (1) and (2).

(1) When tension is applied in a direction substantially perpendicular with respect to the axial line of the reel hub 122 and the recording tape T is wound around the reel hub 122, the recording tape T moves toward the lower flange 126 side that is the small radius side of the reel hub 122 because of the imbalance in the distribution of the surface pressure acting on the recording tape T, and the recording tape T is wound around the reel hub 122.

(2) When the recording tape T is wound around the reel hub 122 such that the side where the radius of curvature of the curvature of the tape edge of the recording tape T is small becomes the small radius side of the reel hub 122, the direction in which the recording tape T moves becomes the lower flange 126 side that is the small radius side of the reel hub 122.

On the other hand, the reel 220 shown in FIG. 19 substantially corresponds to an instance where the metal ring 22B is omitted from the reel 20. The reel 220 is configured by a bottomed circular cylinder-shaped reel hub 222 that configures an axial center portion (winding core portion) of the reel 220, a lower flange 226 that is integrally molded with the lower end portion of the reel hub 222, and an upper flange 224 that is ultrasonically welded to and integrated with the upper end portion of the reel hub 222. Consequently, when the reel hub 222 of the reel 220 becomes deformed by the coiling force F of the recording tape T that is wound around the reel hub 222, for example, the upper flange 224 and the lower flange 226 are affected by that deformation and become deformed such that the distance between the upper flange 224 and the lower flange 226 becomes narrower.

In other words, because the reel hub 222 and the upper and lower flanges 224 and 226 of the reel 220 are integrally configured, the reel 220 has a dependent structure where the reel hub 222 and the upper and lower flanges 224 and 226 are mutually affected by deformation (the upper flange 224 and the lower flange 226 become deformed in accompaniment with deformation of the reel hub 222, or the reel hub 222 becomes deformed in accompaniment with deformation of the upper flange 224 and the lower flange 226). For that reason, in the reel 220 of this configuration, the recording tape T can be caused to move toward the lower flange 226 side that is the small radius side of the reel hub 222 and be wound around the reel hub 222 because of the following synergistic effects (1) to (3).

(1) When tension is applied in a direction substantially perpendicular with respect to the axial line of the reel hub 222 and the recording tape T is wound around the reel hub 222, the surface pressure applied to the reel hub 222 becomes larger on the upper flange 224 side than on the lower flange 226 side of the reel hub 222. For that reason, the amount of deformation of the upper and lower flanges 224 and 226 that become deformed by the coiling of the recording tape T becomes larger on the upper flange 224 side than on the lower flange 226 side. Thus, the recording tape T moves toward the lower flange 226 side that is the small radius side of the reel hub 222 and is wound around the reel hub 222.

(2) When tension is applied in a direction substantially perpendicular with respect to the axial line of the reel hub 222 and the recording tape T is wound around the reel hub 222, the recording tape T moves toward the lower flange 226 side that is the small radius side of the reel hub 222 because of the imbalance in the distribution of the surface pressure acting on the recording tape T, and the recording tape T is wound around the reel hub 222.

(3) When the recording tape T is wound around the reel hub 222 such that the side where the radius of curvature of the curvature of the tape edge of the recording tape T is small becomes the small radius side of the reel hub 222, the direction in which the recording tape T moves becomes the lower flange 226 side that is the small radius side of the reel hub 222.

It will be noted that, when the rigidity of the reel hub 222 is improved, it becomes difficult for the reel hub 222 to become deformed by the coiling force F of the recording tape T, so the effect resulting from the distance between the upper and lower flanges 224 and 226 becoming narrower gradually becomes smaller. Consequently, in this instance, similar to the reel 120, the recording tape T is caused to move toward the lower flange 226 side that is the small radius side of the reel hub 222 and is wound around the reel hub 222 by two synergistic effects—that is, the synergistic effects of (2) and (3). In other words, when the rigidity of the reel hub 222 is improved, structural differences virtually disappear between the reel 220 and the reel 120.

Further, when the recording tape T is wound around the reel hub 22, the resistance acting on the recording tape T from the reel hub 22 becomes larger the higher the rigidity (flexural modulus E in the radial direction) of the reel hub 22 is. Additionally, in the reel hub 22 disposed with the difference ΔR between the radii on both end portions, the recording tape T is caused to move toward the small radius side of the reel hub 22 by the component force of that resistance. In other words, in the reel hub 22, it is easier for the recording tape T to be caused to move toward the small radius side of the reel hub 22 when the rigidity (flexural modulus E in the radial direction) is high and the difference ΔR between the radii is large.

In the reel 20 pertaining to the present embodiment, the rigidity of the reel hub 22 is improved because the metal ring 22B is integrally disposed by insert molding (or by press-fitting or the like) in the resin portion 22A of the reel hub 22. Consequently, in the reel 20 pertaining to the present embodiment, substantially the same action and effects as those of the reel 120 are obtained.

Below, that the recording tape T moves toward the small radius side of the reel hub 22 and is wound around the reel hub 22 when the recording tape T is wound around the reel 20 having this configuration—that is, that the traveling reference of the recording tape T is made to be on the small radius side of the reel hub 22—and that the winding form (winding shape) becomes excellent will be described on the basis of actual experimental data. It will be noted that, for the convenience of explanation, a positive value will represent the difference ΔR between the radii in an instance where the radius of the outer peripheral surface of the reel hub 22 on the upper flange 24 side is larger than the radius of the outer peripheral surface of the reel hub 22 on the lower flange 26 side, and a negative value will represent the difference ΔR between the radii in the opposite instance (when the radius of the outer peripheral surface of the reel hub 22 on the lower flange 26 side is larger than the radius of the outer peripheral surface of the reel hub 22 on the upper flange 24 side).

In FIG. 20 to FIG. 23, there are shown winding form measurement charts when negative curvature recording tape T and positive curvature recording tape T are wound around the reel 20 where the structures and materials of the reel hub 22 are different. That is, FIG. 20 is a winding form measurement chart when negative curvature recording tape T (amount of curvature ΔD=−0.18 mm) is wound around a reel (not shown) that has, similar to the reel 220, a dependent structure where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 associatively acts on/affects each of them, the reel hub 22 is configured by just the resin portion 22A, the material thereof is polycarbonate (PC; elastic modulus is 3.6 GPa) to which 10% glass fiber (GF) has been added, and the difference ΔR between the radii of the reel hub 22 is ΔR=−0.003 mm (−3 μm) (the difference ΔR between the radii is close to ±0).

Additionally, FIG. 21 is a winding form measurement chart when positive curvature recording tape T (amount of curvature ΔD=+0.90 mm) is wound around the reel 20 that has, similar to the reel 220, a dependent structure where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 associatively acts on/affects each of them, the reel hub 22 is configured by just the metal ring 22B, the material thereof is aluminium (Al; elastic modulus is 70 GPa), and the difference ΔR between the radii of the reel hub 22 is ΔR=+0.040 mm (+40 μm).

It will be understood from FIG. 20 and FIG. 21 that the winding measurement chart shown in FIG. 21 is extremely excellent. That is, when the reel 20 has a dependent structure where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 associatively acts on/affects each of them, when the rigidity of the reel hub 22 is raised, the recording tape T can be caused to move toward the small radius side of the reel hub 22 and be wound around the reel hub 22 (the traveling reference of the recording tape T can be made to be on the small radius side of the reel hub 22), and the winding form (winding shape) of the recording tape T can be made excellent. It will be noted that, although FIG. 21 is a winding form measurement chart in an instance where the reel hub 22 is configured by just the metal ring 22B, the same is true even when the reel hub 22 is configured by the resin portion 22A and the metal ring 22B and the elastic modulus thereof is 70 GPa.

On the other hand, FIG. 22 is a winding form measurement chart when negative curvature recording tape T (amount of curvature ΔD=−0.18 mm) is wound around a reel (not shown) that has, similar to the reel 120, an independent structure where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 does not associatively act on/affect each of them, the reel hub 22 is configured by just the resin portion 22A, the material thereof is polycarbonate (PC; elastic modulus is 3.6 GPa) to which 10% glass fiber (GF) has been added, and the difference ΔR between the radii of the reel hub 22 is ΔR+0.002 mm (+2 μm) (the difference ΔR between the radii is close to ±0).

Additionally, FIG. 23 is a winding form measurement chart when negative curvature recording tape T (amount of curvature ΔD=−0.18 mm) is wound around the reel 20 that has, similar to the reel 120, an independent structure where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 does not associatively act on/affect each of them, the reel hub 22 is configured by just the metal ring 22B, the material thereof is aluminium (Al; elastic modulus is 70 GPa), and the difference ΔR between the radii of the reel hub 22 is ΔR=−0.043 mm (−43 μm).

It will be understood from FIG. 22 and FIG. 23 that the winding measurement chart shown in FIG. 23 is extremely excellent. That is, even when the reel has an independent structure where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 does not associatively act on/affect each of them, when the rigidity of the reel hub 22 is raised, the recording tape T can more effectively be caused to move toward the small radius side of the reel hub 22 and be wound around the reel hub 22 (the traveling reference of the recording tape T can be made to be on the small radius side of the reel hub 22), and the winding form (winding shape) of the recording tape T can be made excellent.

It will be noted that, although FIG. 23 is a winding form measurement chart when the reel hub 22 is configured by just the metal ring 22B, the same is true even when the reel hub 22 is configured by the resin portion 22A and the metal ring 22B and the elastic modulus thereof is 70 GPa. Further, in FIG. 23, negative curvature recording tape T is wound around the reel hub 22 and the recording tape T is caused to move toward the upper flange 24 side because the radius of the outer peripheral surface of the reel hub 22 on the upper flange 24 side is smaller than the radius of the outer peripheral surface of the reel hub 22 on the lower flange 26 side (because the radius on the lower flange 26 side is larger than the radius on the upper flange 24 side), but the action and effects thereof are the same as those that are shown in FIG. 21.

Here, Table 2 shows evaluations in regard to the winding form of the recording tape T and the tape edge when the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22—that is, the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width (½ inch width, substantially 12.65 mm) of the recording tape T—is changed. It will be noted that Table 2 shows evaluations in regard to the reel hub 22 where the radius of the outer peripheral surface on the upper flange 24 side is larger than the radius of the outer peripheral surface on the lower flange 26 side, and therefore the “+” sign is omitted.

TABLE 2 Ratio of Difference between Radii on Difference (mm) Upper Flange Side between Radius on and Lower Flange Upper Flange Side Side of Reel Hub and Radius on with respect to Lower Flange Side Tape Width Winding Form State of Example of Reel Hub Dimension of Tape Tape Edge* 1 0.080 0.00632 ∘ x to  2 0.060 0.00474 ∘ □ 3 0.050 0.00400 ∘ ∘ 4 0.040 0.00316 ∘ ∘ 5 0.020 0.00158 □ ∘ 6 0.007 0.00055 □ ∘ 7 0.005 0.00039 □ ∘ 8 0.003 0.00237  ∘ 9 0.000 0.00000 x to  ∘ *∘ = extremely good; □ = good;  = somewhat bad; x = bad

As will be understood from Table 2, the winding form is not good when the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is less than 0.005 mm (5 μm) (when the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is less than 0.00039). In other words, either the effect of causing the recording tape T to be wound around the reel hub 22 to move toward the small radius side of the reel hub 22 is not obtained, or it is also conceivable that the shape of the reel hub 22 cannot be accurately grasped due to the precision of measurement.

Further, the winding form is good when the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is greater than 0.060 mm (60 μm) (when the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is greater than 0.00474), but radiation in the radial direction whose origin point is in the vicinity of the reel hub 22 and tape edge damage can be seen.

In other words, it will be understood that, when the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 becomes larger, the component force of resistance acting on the recording tape T becomes larger when the recording tape T is wound around the reel hub 22, so it becomes easier for the recording tape T to move toward the lower flange 26 side that is the small radius side of the reel hub 22 and the winding form becomes good, but when the difference ΔR between the radii is too large, there is the danger for the recording tape T to be pushed excessively toward the lower flange 26 side and sustain tape edge damage such that so-called radiation occurs, for the recording tape T to interfere with the lower flange 26 during travel and further sustain tape edge damage, and in addition for phenomena that develop into defects such as cinching to occur.

For this reason, in the reel 20, the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 is in the range of 5 μm to 60 μm with respect to the width of the recording tape T (½ inch width, substantially 12.65 mm). In other words, the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is in the range of 0.00039 to 0.00474.

Further, when the amount of curvature ΔD of the recording tape T is too small (close to 0), the polarity of the recording tape T (the direction in which the recording tape T moves as it is wound around the reel hub) is undetermined, the position of the recording tape T fluctuates in the vertical direction, it becomes easier for disorderly winding to occur, and the winding surface becomes a so-called rough winding state. On the other hand, when the amount of curvature ΔD of the recording tape T is too large and the recording tape T has positive curvature, the recording tape T is pushed excessively toward the lower flange 26 side and sustains tape edge damage such that so-called radiation occurs, the recording tape T interferes with the lower flange 26 during travel and further sustains tape edge damage, and in addition, phenomena that develop into defects such as cinching occur, and the tape traveling position moves excessively toward one side. For this reason, it is necessary to set the amount of curvature of the recording tape T to an appropriate amount of curvature ΔD. In Table 3, there are shown amounts of curvature ΔD of the recording tape T and states of the tape edge.

TABLE 3 Amount of Curvature of State of Recording Tape (mm) Tape Edge* 1 0.10  2 0.15 □ 3 0.20 □ 4 0.50 ∘ 5 1.00 ∘ 6 1.50 ∘ 7 2.00 ∘ 8 2.50 □ 9 3.00  *∘ = extremely good; □ = good;  = somewhat bad; x = bad

From the results of Table 3, it will be understood that problems do not arise in the tape edge when the amount of curvature ΔD of the recording tape T is in the range of 0.15 mm to 2.5 mm. For this reason, in the present embodiment, the absolute value of the amount of curvature ΔD of the recording tape T is set such that ΔD=0.15 mm to 2.5 mm. Thus, in the recording tape T, a tape traveling position that is appropriate and stable and a state where there is little disorderly winding can be achieved. In other words, disorderly winding is controlled, and the winding surface becomes closer to orderly winding.

It will be will noted that it is more preferable for the absolute value of the amount of curvature ΔD to be in the range of ΔD=0.5 mm to 2.0 mm because the moving of the tape edge toward the lower flange 26 side becomes appropriate when the recording tape T is wound around the reel hub 22. That is, there becomes less fluctuation in the position of the recording tape T in the axial direction of the reel hub 22 during travel, disorderly winding is controlled, and the recording tape T is orderly wound in a state along the lower flange 26 side, so tape edge damage is reduced in the recording tape T.

Consequently, when the amount of curvature ΔD of the recording tape T is small, such as 0.5 mm to 2.0 mm (when the radius of curvature of the curvature of the tape edge of the recording tape T is large), the recording tape T functions sufficiently even when the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 is 5 μm to 60 μm with respect to the width of the recording tape T (the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T is 0.00039 to 0.00474).

However, there are also instances where, from the standpoints of the productivity of the reel 20 and design freedom, the amount of curvature ΔD of the recording tape T is set large, such as 2.5 mm (there are also instances where the radius of curvature of the curvature of the tape edge of the recording tape T is set small). In these instances, it is preferable for the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 to be in the range of 7 μm to 50 μm with respect to the width of the recording tape T (for the ratio of the difference ΔR between the radius on the upper flange 24 side of the reel hub 22 and the radius on the lower flange 26 side of the reel hub 22 with respect to the width of the recording tape T to be 0.00055 to 0.00400).

When the difference ΔR between the radii is in this range, the recording tape T is not excessively pushed against the inner surface on the lower flange 26 side of the reel hub 22 when the recording tape T is wound around the reel hub 22, the recording tape T does not interfere with the lower flange 26, and the moving of the tape edge of the recording tape T toward the lower flange 26 side becomes appropriate. In other words, even when the amount of curvature ΔD is 2.5 mm, bad traveling phenomena such as tape edge damage and abnormal sounds can be controlled, and an excellent winding form is obtained.

It will be noted that the necessary minimum rigidity of the reel hub 22 (the flexural modulus E in the radial direction of the reel hub 22) is determined from the experimental results in Table 1. That is, as will be understood from Table 1 and also from FIG. 20 and FIG. 22, the winding form is not good when the flexural modulus E in the radial direction of the reel hub 22 is 3.6 GPa. However, it will be understood that there are no problems as long as the flexural modulus E in the radial direction of the reel hub 22 is equal to or greater than 16.9 GPa.

Here, the numerical value 16.9 GPa is a value when it is assumed that 5% error is included in the elastic modulus E_(a) of the resin portion 22A when its thickness is a and in the elastic modulus E_(b) of the metal ring 22B when its thickness is b, and when this error is removed, the flexural modulus E becomes 16.0 GPa. Thus, in the present embodiment, the flexural modulus E in the radial direction of the reel hub 22 is made equal to or greater than 16.0 GPa. Additionally, the flexural modulus E is more preferably equal to or greater than 19.2 GPa (a numerical value where 5% error is removed from 20.2 GPa).

In this manner, by making the flexural modulus E in the radial direction of the reel hub 22 equal to or greater than 16.0 GPa and preferably equal to or greater than 19.2 GPa, the recording tape T that is wound around the reel hub 22 can be appropriately caused to move toward the small radius side (the lower flange 26 side) of the reel hub 22, and the winding form (winding shape) of the recording tape T can be made excellent.

As described above, in the reel 20 pertaining to the present embodiment, the flexural modulus E in the radial direction of the reel hub 22 is made equal to or greater than 16.0 GPa, and the radius on the upper flange 24 side of the reel hub 22 is made larger than the radius on the lower flange 26 side of the reel hub 22, so the following actions (1) and (2) are provided.

(1) When tension is applied in a direction substantially perpendicular with respect to the axial line of the reel hub 22 and the recording tape T is wound around the reel hub 22, the recording tape T moves toward the lower flange 26 side that is the small radius side of the reel hub 22 because of the imbalance in the distribution of the surface pressure acting on the recording tape T, and the recording tape T is wound around the reel hub 22.

(2) When the recording tape T is wound around the reel hub 22 such that the side where the radius of curvature of the curvature of the tape edge of the recording tape T becomes the small radius side of the reel hub 22, the direction in which the recording tape T moves becomes the lower flange 26 side that is the small radius side of the reel hub 22.

In other words, according to the present embodiment, because of the synergistic effects of (1) and (2), the recording tape T can be appropriately caused to move toward the lower flange 26 side that is the small radius side of the reel hub 22 and be wound around the reel hub 22. Consequently, fluctuation of the recording tape T in the axial direction of the reel hub 22 can be controlled, disorderly winding of the recording tape T can be controlled, and orderly windability can be improved (the winding form can be made excellent).

Thus, the occurrence of a step or one-layer protrusion or plural-layer protrusion from the winding surface of the recording tape T that has been wound around the reel hub 22 can be controlled, and problems that occur as a result of the one-layer protruding recording tape T striking the upper flange 24 or the lower flange 26, bending and sustaining tape edge damage when the recording tape T receives a shock such as during transport, or when the recording tape cartridge is dropped, or during handling can be reduced.

Additionally, the tape traveling position can be stabilized because the position of the recording tape T can be controlled from fluctuating in the axial direction of the reel hub 82 even during travel of the recording tape T inside the drive device 70. In particular, fluctuation of the recording tape T in the axial direction of the reel hub 82 of the take-up reel 80, whose shape becomes complex and which is difficult to make highly precise because it is disposed with the function of housing the leader block 85, can be controlled even by the reel 20. For this reason, servo signal S reading errors (servo tracking errors) and data signal recording and playback errors that occur during travel can be reduced even in high density recording, and a reduction of so-called position error signals and off-track can be expected.

Further, when the thickness of the recording tape T is thick, the rigidity of the recording tape T also increases, so the strength of the tape edge increases, and it becomes difficult for problems such as tape edge damage to occur with respect also to pushing against the upper and lower flanges 24 and 26, shock, friction, and wear. However, there is a trend for the thickness of recent recording tape T to be made thin in order to increase the recording capacity of the recording tape T per cartridge, and in an instance of recording tape T with the same thickness, the distribution of stress acting in the width direction of the recording tape T when the same tension is applied to the recording tape T and the recording tape T is wound around the reel 20 (the reel hub 22) changes.

In other words, the rigidity of the recording tape T that is wound around the reel hub drops, the strength of the tape edges drops, and kinks resulting from one-layer protrusion and tape edge damage during travel become an even greater problem than has been the case up to now. In contrast, the reel 20 of the present embodiment can control fluctuation in the position of the recording tape T, so the reel 20 can control the amount of protrusion of the one-layer protrusion phenomenon and the rate of occurrence itself. Thus, this becomes effective with respect to recording tape T whose thickness has been made thin (e.g., 6.9 μm or less).

Further, the orientation of the curvature of the recording tape T can also be changed by a heat treatment. That is, by performing an appropriate heat treatment in a state where the recording tape T has been taken up on a reel (not shown) where the outer peripheral surface of the reel hub 22 is formed in a tapered shape, uniform curvature can be imparted by the shape fixing effect resulting from the creep phenomenon, and an excellent winding habit can be imparted to the recording tape. In the present embodiment, positive curvature recording tape T is used, but negative curvature recording tape T may also be used by making the radius of the outer peripheral surface of the reel hub 22 on the upper flange 24 side smaller than the radius of the outer peripheral surface of the reel hub 22 on the lower flange 26 side. The traveling reference in this instance becomes the upper flange 24 side (see FIG. 23).

Further, in the present embodiment, the metal ring 22B is integrated with the resin portion 22A by insert molding to form the reel hub 22, but the metal ring 22B may also be integrated with the resin portion 22B by press-fitting the metal ring 22B into the inside of the resin portion 22A. Moreover, the material of the metal ring 22B is not limited to aluminium and may also be stainless steel whose flexural modulus E is 190 GPa or greater, for example. Further, when the reel hub 22 is given a configuration disposed with the metal ring 22B (also includes instances where the reel hub 22 is configured by just the metal ring 22B), the rigidity of the reel hub 22 can be easily raised, but this does not mean that the metal ring 22B is invariably necessary. The reel hub 22 may also be configured by just the resin portion 22A by adding a strengthening agent such as glass fiber during molding of the reel hub 22 so that the desired rigidity (a flexural modulus E equal to or greater than 16.0 GPa) can be ensured.

Further, in the reel 20 pertaining to the present embodiment, the reel hub 22 and the lower flange 26 are integrally molded and the upper flange 24 is welded to the reel hub 22, but the reel hub 22 and the upper flange 24 may be integrally molded and the lower flange 26 may be welded to the reel hub 22, or the upper flange 24 and the lower flange 26 may be welded to both end portions of the reel hub 22, or the reel hub 22, the upper flange 24 and the lower flange 26 may be integrally molded. In other words, “integrally” mentioned in the present embodiment refers to a configuration where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 associatively acts on/affects each of them and is a configuration where the upper flange 24 and/or the lower flange 26 becomes deformed in accompaniment with deformation of the reel hub 22 or where the reel hub 22 becomes deformed in accompaniment with deformation of the upper flange 24 and/or the lower flange 26.

Similarly, a configuration where the reel hub 22, the upper flange 24 and the lower flange 26 are separately molded is also included in the reel 20 pertaining to the present embodiment. That is, “separately” mentioned in the present embodiment refers to a configuration where deformation of the reel hub 22, the upper flange 24 and the lower flange 26 does not associatively act on/affect each of them (they are mutually independent). It will be noted that the same is true also in regard to the take-up reel 80 as it is for the reel 20. Further, in the present embodiment, an example has been described where the invention is applied to the recording tape cartridge 10 that is configured by housing the reel 20 singly inside the case 12, but the present invention is not limited to this. For example, the present invention may of course also be applied to a two-reel type recording tape cassette where two reels are housed inside a case. 

1. A tape reel comprising: a hub around which recording tape is wound; and flanges disposed on both end portions of the hub, wherein the elastic modulus in a radial direction of the hub is equal to or greater than 16.0 GPa, the hub includes different radii on one end side thereof and another end side thereof, and the recording tape is wound around the hub such that the side where the radius of curvature of the curvature of the tape edge of the recording tape is small corresponds to the small radius side of the hub.
 2. The tape reel of claim 1, wherein the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape is equal to or greater than 0.00039 and equal to or less than 0.00474.
 3. The tape reel of claim 1, wherein the width of the recording tape is substantially 12.65 mm, and the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is equal to or greater than 5 μm and equal to or less than 60 μm.
 4. The tape reel of claim 1, wherein the absolute value of the amount of curvature of the recording tape is equal to or greater than 0.15 mm and equal to or less than 2.5 mm.
 5. The tape reel of claim 1, wherein the hub is configured to include a metal that is disposed integrally with a resin by insert molding or press-fitting.
 6. The tape reel of claim 1, wherein the thickness of the recording tape is equal to or less than 7.5 μm.
 7. The tape reel of claim 1, wherein the recording tape includes servo signals that serve as a positioning reference of a recording and playback head of a drive device, and the tape edge of the recording tape that has been wound around the hub that is on the small radius side of an outer peripheral surface of the hub serves as a servo tracking control reference during travel of the recording tape.
 8. A recording tape cartridge comprising the tape reel of claim 1 and a case that rotatably houses the tape reel.
 9. The recording tape cartridge of claim 8, wherein the tape cartridge has a single tape reel configuration.
 10. A take-up reel that is disposed inside a drive device and around which is wound recording tape that has been pulled out from a recording tape cartridge, the take-up reel comprising: a hub around which the recording tape is wound; and flanges disposed on both end portions of the hub, wherein the elastic modulus in a radial direction of the hub is equal to or greater than 16.0 GPa, the hub includes different radii on one end side thereof and another end side thereof, and the side where the radius of curvature of the curvature of a tape edge of the recording tape is small is wound around the small radius side of the hub.
 11. The take-up reel of claim 10, wherein the ratio of the difference between the radius on the one end side of the hub and the radius on the other end side of the hub with respect to the width of the recording tape that is wound around the hub is equal to or greater than 0.00039 and equal to or less than 0.00474.
 12. The take-up reel of claim 10, wherein the width of the recording tape that is wound around the hub is substantially 12.65 mm, and the difference between the radius on the one end side of the hub and the radius on the other end side of the hub is equal to or greater than 5 μm and equal to or less than 60 μm.
 13. The take-up reel of claim 10, wherein the absolute value of the amount of curvature of the recording tape that is wound around the hub is equal to or greater than 0.15 mm and equal to or less than 2.5 mm.
 14. The take-up reel of claim 10, wherein the hub is configured to include a metal that is disposed integrally with a resin by insert molding or press-fitting.
 15. The take-up reel of claim 10, wherein the thickness of the recording tape that is wound around the hub is equal to or less than 7.5 μm.
 16. The take-up reel of claim 10, wherein the recording tape that is wound around the hub includes servo signals that serve as a positioning reference of a recording and playback head disposed in the drive device, and the tape edge of the recording tape that has been wound around the hub that is positioned on the small radius side of an outer peripheral surface of the hub serves as a servo tracking control reference during travel of the recording tape.
 17. A pullout member that pulls out recording tape from a recording tape cartridge, is housed in the hub of the take-up reel of claim 10, and is disposed with a take-up surface that configures part of an outer peripheral surface of the hub, wherein the elastic modulus of the take-up surface is equal to or greater than 16.0 GPa, the take-up surface includes different radii on one end side thereof and another end side thereof, and the take-up surface and the outer peripheral surface of the hub become substantially even in a state where the pullout member is housed in the hub.
 18. A drive device including the take-up reel of claim 10 around which is wound recording tape that has been pulled out from a recording tape cartridge that has been loaded into the drive device.
 19. A drive device of a recording tape cartridge, the drive device comprising: a take-up reel that includes a hub around which recording tape is wound and flanges disposed on both end portions of the hub, with the recording tape that has been pulled out from the recording tape cartridge being wound around the take-up reel; and a pullout member that pulls out the recording tape from the recording tape cartridge and includes a take-up surface that configures part of an outer peripheral surface of the hub when the pullout member is housed in the hub of the take-up reel, wherein the elastic modulus in a radial direction of the hub and the elastic modulus of the take-up surface are equal to or greater than 16.0 GPa, the hub and the take-up surface each include different radii on one end side thereof and another end side thereof, the take-up surface of the pullout member becomes substantially even with an outer peripheral surface of the hub in a state where the pullout member is housed in the hub, and the side where the radius of curvature of the curvature of a tape edge of the recording tape is small is wound around the small radius side of the hub. 